This invention relates to anti-backlash spring-mounted nuts, and more particularly to relatively small nuts of this type which are used with lead screws in precision movements or transverses.
The invention concerns improvements in the anti-backlash nuts described and claimed in my U.S. Pat. Nos. 3,831,460 and 3,977,269 issued respectively on Aug. 27th, 1974 and Aug. 31, 1976 and having the same ownership as the present invention and application.
In my U.S. Pat. No. 3,831,460 there is disclosed a one-piece spring-mounted anti-backlash nut construction wherein a split nut portion is carried by an aligning-type base portion, the latter having four pairs of strategically-disposed slots by which it functions somewhat in the manner of a universal joint to insure the proper coaction of the nut with the lead screw. The use of four such pairs of slots required forming or machining operations which undesirably increased the cost of the product, even though the operation of the finished piece was completely satisfactory. Moreover, the use of multiple slots could adversely affect the strength and load limits of the nut construction.
My U.S. Pat. No. 3,977,269 disclosed a more compact arrangement of self-aligning anti-backlash nut wherein the spring-mount base portion was exterior to and concentric with the nut portion, and wherein it was possible to utilize only three pairs of slots in the spring mount, to effect the aligning of the nut on the screw. By reducing the number of slots, the fabrication cost was lessened, and also the possibility existed of leaving more strength in the assemblage, while still having superior performance. But cost of production still constituted an important factor, and for certain specific uses the cost-performance ratio did not fit into the requirements laid down.